WO 97/42985 discloses a wound dressing comprising a layer of absorbent foam material which includes a pattern of holes. The holes open out on that side of the foam material which lies proximal to the wearer's skin when the dressing is worn, and the layer of foam material is coated with a layer of skin-adhering hydrophobic gel, wherein those end parts of the walls of the holes in the foam material that lie proximal to the wearer's skin when the dressing is worn are gel-coated. Nothing is disclosed about including particular antimicrobial or antibacterial compounds in the dressing.
U.S. Pat. No. 5,662,913 describes using silver salts that are stabilised by forming complexes with acyclic polyether polymers. Furthermore, the anions of the silver salts are present in excess in relation to the silver ions. The stabilised silver salt complexes of U.S. Pat. No. 5,662,913 can be included in foam structures. The object of the invention disclosed in this patent is to provide photo-stable, non-staining antimicrobial metal compositions for protection against infections, and to render a polyurethane-based foam object antimicrobial. Nothing is disclosed about controlling the release of silver from a polyurethane structure.
WO 2004/007595 discloses a flexible cellular polyurethane foam product which has been produced in the presence of a controlled release silver component. The release of silver from the structure is generally slow, which is advantageous in some applications but may not be sufficient in other applications.
EP-A1-1 486 523 and U.S. Pat. No. 4,937,273 both relate to polyurethane foams containing antimicrobial silver bound to zeolite particles. The release of silver from the structure is generally slow, which is advantageous in some applications but may not be sufficient in other applications.
WO 2002/062403 discloses production of wound dressings with releasable silver complexes formed with metals of group IV of the periodic system of elements, and in particular silver zirconium salts. Nothing is disclosed regarding the silver salts in claim 1 of the present application.
EP-A1-0 059 049 relates to wound dressings containing silver sulphadiazine. Nothing is disclosed regarding the silver salts in claim 1 of the present application.
Different wounds require different release patterns for antimicrobial agents, such as silver. For infected wounds and wounds that may become easily infected, it would, however, be desirable to use a dressing which initially would be capable of releasing large amounts of anti-microbial silver and which would be capable of maintaining such a release for a prolonged period of time.